KR102551299B1 - Multilayer ceramic capacitor and method of manufacturing the same - Google Patents

Abstract

One aspect of the present invention includes a body including a dielectric layer and internal electrodes, and an external electrode disposed on one surface of the body, wherein the external electrode is disposed on one surface of the body and is in contact with the internal electrode, A first electrode layer containing titanium nitride (TiN); A multilayer ceramic capacitor including a second electrode layer disposed on the first electrode layer is provided.

Description

Multilayer ceramic capacitor and its manufacturing method {MULTILAYER CERAMIC CAPACITOR AND METHOD OF MANUFACTURING THE SAME}

The present invention relates to a multilayer ceramic capacitor and a manufacturing method thereof.

With the trend of miniaturization and high capacitance of multilayer ceramic capacitors (MLCCs), the importance of increasing the effective volume ratio (the ratio of volume to total volume that contributes to capacity) of multilayer ceramic capacitors is increasing.

Conventionally, when forming external electrodes, a method of dipping the surface of the body where internal electrodes are exposed using a paste containing a conductive metal has been mainly used.

However, the thickness of the external electrode formed by the dipping method is not uniform, and the external electrode is formed too thin at the corner of the body, while the external electrode is formed too thick in other parts. For this reason, it is not only difficult to secure a high effective volume ratio, but also when a plating layer is formed on the external electrode to increase the connectivity and mountability of the multilayer ceramic capacitor, the plating solution permeates into the body, reducing the reliability of the multilayer ceramic capacitor. There was a problem with

One of the objects of the present invention is to form a thin and dense primary electrode layer on the body of a multilayer ceramic capacitor, so that even when the thickness of an external electrode is thin, sufficient moisture resistance reliability can be secured and the effective volume ratio can be improved. We want to provide a capacitor.

One aspect of the present invention includes a body including a dielectric layer and internal electrodes, and external electrodes disposed on one surface of the body, wherein the external electrodes are disposed on one surface of the body and are in contact with the internal electrodes, and titanium nitride A first electrode layer containing (TiN); and a second electrode layer disposed on the first electrode layer.

Another aspect of the present invention includes preparing a body including a dielectric layer and internal electrodes; forming a first electrode layer containing titanium nitride (TiN) on the front surface of the body by an atomic layer deposition method; forming a second electrode layer on a portion where first and second external electrodes are to be formed in the body on which the first electrode layer is formed; and etching and removing exposed portions of the first electrode layer from the body on which the second electrode layer is formed.

In the multilayer ceramic capacitor according to an embodiment of the present invention, by forming a thin and dense primary electrode layer on the body of the multilayer ceramic capacitor, sufficient moisture resistance reliability can be secured even when the thickness of the external electrode is thin, and the effective volume ratio can be improved. there is.

1 schematically illustrates a perspective view of a multilayer ceramic capacitor according to an exemplary embodiment of the present invention.
FIG. 2 schematically illustrates a cross-sectional view taken along line II′ of FIG. 1 .
FIG. 3 schematically illustrates an enlarged cross-sectional view of portion A of FIG. 2 .
FIG. 4 schematically illustrates an enlarged cross-sectional view of portion B of FIG. 2 .
5 schematically illustrates an enlarged cross-sectional view of a portion B of a multilayer ceramic capacitor according to another embodiment of the present invention.
6 schematically illustrates an enlarged cross-sectional view of a portion B of a multilayer ceramic capacitor according to another embodiment of the present invention.
7 to 10 are perspective views schematically illustrating each step of a method of manufacturing a multilayer ceramic capacitor, which is another aspect of the present invention.

Hereinafter, embodiments of the present invention will be described with reference to specific embodiments and accompanying drawings. However, the embodiments of the present invention can be modified in many different forms, and the scope of the present invention is not limited to the embodiments described below. In addition, the embodiments of the present invention are provided to more completely explain the present invention to those skilled in the art. Accordingly, the shapes and sizes of elements in the drawings may be exaggerated for clarity. In addition, components having the same function within the scope of the same concept shown in the drawings of each embodiment are described using the same reference numerals.

In addition, in order to clearly describe the present invention in the drawings, parts irrelevant to the description are omitted, and the thickness is enlarged in order to clearly express various layers and regions, and components having the same function within the scope of the same idea are shown with the same reference. Explain using symbols. Furthermore, throughout the specification, when a certain component is said to "include", it means that it may further include other components without excluding other components unless otherwise stated.

In the drawing, the X direction may be understood as a first direction or longitudinal direction, the Y direction as a second direction or width direction, and the Z direction as a third direction, thickness direction or stacking direction, but is not limited thereto.

multilayer ceramic capacitors

1 schematically illustrates a perspective view of a multilayer ceramic capacitor according to an exemplary embodiment of the present invention. FIG. 2 is a schematic cross-sectional view taken along the line II′ of FIG. 1. Referring to FIG. FIG. 3 schematically illustrates an enlarged cross-sectional view of portion A of FIG. 2 . FIG. 4 schematically illustrates an enlarged cross-sectional view of part B of FIG. 3 .

Hereinafter, a multilayer ceramic capacitor 100 according to an exemplary embodiment of the present invention will be described with reference to FIGS. 1 to 4 .

Referring to FIG. 1 , a multilayer ceramic capacitor 100 according to an embodiment of the present invention includes a body 110 and first and second external electrodes 130 and 140 disposed outside the body 110. .

Body 110 is connected to the first and second surfaces (1, 2), the first and second surfaces (1, 2) opposed to each other in the thickness direction (Z direction) and mutually in the width direction (Y direction) It is connected to the opposing third and fourth faces 3 and 4, the first and second faces 1 and 2, is connected to the third and fourth faces 3 and 4, and is connected to each other in the longitudinal direction (X direction). It may have opposing fifth and sixth faces 5 and 6 .

Referring to FIG. 2 , the body 110 includes a dielectric layer 111 and internal electrodes 121 and 122 disposed to be alternately exposed through the third and fourth surfaces 3 and 4 with the dielectric layer 111 interposed therebetween. includes

The body 110 is formed by laminating a plurality of dielectric layers 111 in the thickness (Z) direction and then firing them, and the shape, size and number of stacked dielectric layers 111 of the body 110 are shown in the present embodiment. It is not limited.

The plurality of dielectric layers 111 forming the body 110 are in a fired state, and the boundary between adjacent dielectric layers 111 can be integrated to the extent that it is difficult to confirm without using a scanning electron microscope (SEM). there is.

A raw material forming the dielectric layer 111 is not particularly limited as long as sufficient capacitance can be obtained, and may be, for example, barium titanate (BaTiO ₃ ) powder. The material forming the dielectric layer 111 may include various ceramic additives, organic solvents, plasticizers, binders, dispersants, and the like added to powder such as barium titanate (BaTiO ₃ ) according to the purpose of the present invention.

The internal electrodes 121 and 122 may include a first internal electrode 121 exposed through the third surface 3 and a second internal electrode 122 exposed through the fourth surface 4 .

The first and second internal electrodes 121 and 122 are a pair of electrodes having different polarities and are electrically insulated from each other by the dielectric layer 111 disposed in the middle.

The first and second internal electrodes 121 and 122 are disposed outside the body 110 by being alternately exposed to the third and fourth surfaces 3 and 4 in the longitudinal direction (X direction) of the body 110 . connected to the first and second external electrodes 130 and 140 respectively.

Thicknesses of the first and second internal electrodes 121 and 122 may be determined according to a purpose.

For example, the widths of the first and second internal electrodes 121 and 122 may be formed to satisfy the range of 0.2 to 1.0 μm in consideration of the size of the body 110, but are not necessarily limited thereto.

The first and second internal electrodes 121 and 122 are made of nickel (Ni), copper (Cu), palladium (Pd), silver (Ag), lead (Pb), or platinum (Pt) alone or alloys thereof. A conductive metal may be included.

The upper and lower portions of the body 110 may include cover layers 112 formed by stacking dielectric layers in which internal electrodes are not formed, respectively. The cover layer 112 may serve to maintain reliability of the multilayer ceramic capacitor against external impact.

The external electrodes 130 and 140 are disposed on one surface of the body 110, contact the internal electrodes 121 and 122, and include the first electrode layers 131 and 141 including TiN and the first electrode layers 131 and 141 ) and second electrode layers 132 and 142 disposed on it.

The external electrodes 130 and 140 may include first and second external electrodes 130 and 140 respectively connected to the first and second internal electrodes 121 and 122 .

At this time, the first and second external electrodes 130 and 140 are connection parts formed on the third and fourth surfaces 3 and 4 of the body 110, respectively, and the first, second, and second electrodes of the body at the connection part. It may include a band portion extending to portions of the fifth and sixth surfaces 1, 2, 5, and 6, and a corner portion where the connection portion and the band portion come into contact.

With reference to FIGS. 3 and 4 , structures of the first and second external electrodes 130 and 140 of the multilayer ceramic capacitor according to an exemplary embodiment will be described in more detail. 3 and 4 are enlarged views of the first external electrode 130 , but the description thereof may also be applied to the second external electrode 140 .

The first electrode layer 131 includes TiN (titanium nitride). Also, it may be made only of TiN.

TiN has advantages such as excellent acid resistance and durability, low possibility of breakage during processing, and excellent adhesion to ceramics and metals. In addition, it has a low moisture permeability and serves to improve moisture resistance reliability.

The first electrode layer 131 may be formed by an atomic layer deposition (ALD) method.

The ALD method is a technology that deposits a thin film or protective film on the surface of a substrate during the semiconductor process. Unlike the existing deposition technology that chemically coats a thin film, it is a technology that grows a thin film by stacking atomic layers one by one. The ALD method has the advantage of excellent step-coverage, easy thin film thickness control, and the ability to form a uniform thin film.

In addition, when the first electrode layer is formed by the ALD method using TiN, connectivity between the internal electrode and the external electrode can be sufficiently secured even with a thickness of about 5 nm. Accordingly, the thickness of the external electrode can be reduced and the effective volume fraction can be increased.

The thickness of the first electrode layer 131 may be 10 to 500 nm.

This is because when the thickness of the first electrode layer 131 is less than 10 nm, there is a concern that sufficient moisture barrier effect may not be obtained, and when the thickness exceeds 500 nm, there is a concern that the ESR may increase.

Table 1 below shows the results of measuring the change in moisture resistance reliability according to the maximum thickness of the first electrode layer by forming the first electrode layer with TiN using an atomic layer deposition method and forming the second electrode layer with a resin-based electrode.

Moisture resistance reliability was tested by applying 9.5V voltage for 20 hours under the conditions of 85℃ and 85%, and as a result of testing 100 samples for each sample, the number of cases in which reliability failure did not occur is expressed in %.

Sample No Thin film layer thickness (nm) Moisture Reliability (%) One* One 28 2* 3 27 3* 5 24 4* 7 73 5 10 100 6 19 100 7 51 100 8 70 100 9 98 100 10 201 100 11 294 100 12 397 100 13 499 100

Referring to Table 1, it can be seen that the moisture resistance reliability is 100% when the thickness of the first electrode layer is 10 nm or more.

Referring to FIG. 3 , when the thickness of the connection portion of the first electrode layer is defined as t1 and the thickness of the corner portion of the first electrode layer is defined as t2, t2/t1 may be equal to or greater than 0.9. Since the first electrode layer is formed using the ALD method, the overall thickness of the first electrode layer can be uniformly adjusted so that t2/t1 becomes 0.9 or more. Accordingly, the first electrode layer may be formed to a sufficient thickness up to the corner portion to block penetration of moisture and plating solution.

Also, when the thickness of the band portion of the first electrode layer is defined as t3, t3/t1 may be 0.9 to 1.1. That is, the thickness deviation between the connection part and the band part may be 10% or less.

As described above, sufficient moisture resistance and electrode connectivity can be secured by the first electrode layer, so there is no need to specifically limit the second electrode layer. can have

FIG. 4 schematically illustrates an enlarged cross-sectional view of part B of FIG. 3 .

Referring to FIG. 4 , the second electrode layer may be a firing electrode 132 including a conductive metal 132a and a glass 132b. The component of the glass 132b helps form an alloy between the conductive metal 132a and the first electrode layer 131 and acts as a binder to seal.

In this case, as an example of obtaining the fired electrode 132, a paste including the conductive metal 132a and the glass 132b is applied on the first electrode layer and then fired to form the fired electrode 132. there is.

In this case, the conductive metal 132a may be Cu.

5 schematically illustrates an enlarged cross-sectional view of a portion B of a multilayer ceramic capacitor according to another embodiment of the present invention.

Referring to FIG. 5 , the second electrode layer may be a resin-based electrode 132′ including a plurality of metal particles 132a′ and a base resin 132b′.

The resin-based electrode 132' has a form in which a plurality of metal particles 132a' are dispersed in a base resin 132b'. In this case, as an example of obtaining a resin-based electrode, a paste in which metal particles are dispersed in a base resin may be used, and the applied paste is formed through a drying and curing process, so that an external electrode is formed by conventional firing. Unlike the method, the metal particles are not melted and may exist in the resin-based electrode in the form of particles.

In this case, the metal particles 132a′ may be one or more of Cu, Ni, and Ag.

Meanwhile, the metal particles 132a′ may be formed not only in a spherical shape, but also in a flake shape if necessary, or a mixed type of a spherical shape and a flake shape.

The base resin 132b' may include a thermosetting resin.

In this case, the thermosetting resin may be, for example, an epoxy resin, but the present invention is not limited thereto.

The base resin 132b' serves to mechanically bond the first electrode layer 131 and the plating layer (not shown).

6 schematically illustrates an enlarged cross-sectional view of a portion B of a multilayer ceramic capacitor according to another embodiment of the present invention.

Referring to FIG. 6, the second electrode layer 132`` includes a plurality of metal particles 132a``, a conductive connection portion 132c`` surrounding the plurality of metal particles, a base resin 132b``, and the plurality of metal particles 132a``. It may be a resin-based electrode 132`` including an intermetallic compound 132d`` in contact with the first electrode layer 131 and the conductive connection portion 132c``.

The resin-based electrode 132`` including the intermetallic compound 132d`` has a form in which a plurality of metal particles 132a`` are dispersed in the base resin 132b``.

In this case, the metal particles 132a`` may be one or more of Cu, Ni, Ag, Ag-coated Cu, and Sn-coated Cu.

Meanwhile, the metal particles 132a″ may be formed not only in a spherical shape but also in a flake shape if necessary, or a mixed type of a spherical shape and a flake shape.

The base resin 132b`` may include a thermosetting resin.

In this case, the thermosetting resin may be, for example, an epoxy resin, but the present invention is not limited thereto.

The base resin 132b`` serves to mechanically bond the first electrode layer 131 and the plating layer (not shown).

The conductive connection part 132c`` serves to surround and connect a plurality of metal particles 132a`` in a molten state, thereby minimizing stress inside the body 110 and improving high-temperature load and moisture resistance load characteristics. can improve

In this case, the metal included in the conductive connection portion 132c`` may have a melting point lower than the curing temperature of the base resin 132b``.

That is, since the conductive connection portion 132c″ has a melting point lower than the curing temperature of the base resin 132b″, it melts during the drying and curing process, and as shown in FIG. 5, the conductive connection portion 132c′ `) can cover the metal particles 132a`` in a molten state.

At this time, the metal of the conductive connection is preferably 300 ℃? It may be made of the following low melting point metals. For example, it may include Sn having a melting point of 213 to 220°C?

The intermetallic compound 132d`` is disposed to be in contact with the first electrode layer 131, and serves to reduce contact resistance between the resin-based electrode 132`` and the first electrode layer 131. In addition, the intermetallic compound 132d`` comes into contact with the conductive connection portion 132c`` and serves to connect the first electrode layer 131 and the conductive connection portion 132c``.

In this case, as an example for obtaining the resin-based electrode 132``, one or more metal particles of Cu, Ni, Ag, Ag-coated Cu, and Sn-coated Cu on the base resin and the base resin 132b`` ), a paste in which a low melting point metal having a melting point lower than the curing temperature is dispersed can be used, and the applied paste is formed through a drying and curing process, so unlike the conventional method of forming an external electrode by firing, metal particles It is not melted and may exist in the resin-based electrode in the form of particles.

In this case, the low melting point metal may be one or more of Sn/Bi, Sn-Pb, Sn-Cu, Sn-Ag, and Sn-Ag-Cu.

Meanwhile, the external electrodes 130 and 140 may further include plating layers (not shown) formed on the second electrode layers 132 and 142 .

Also, the plating layer may have a multilayer structure. For example, the plating layer may have a multilayer structure of Ni/Sn, Sn/Ni/Sn, Cu/Ni/Sn, or the like.

Manufacturing method of multilayer ceramic capacitor

7 to 10 are perspective views schematically illustrating each step of a method of manufacturing a multilayer ceramic capacitor according to another aspect of the present invention.

A method of manufacturing a multilayer ceramic capacitor according to another aspect of the present invention includes preparing a body including a dielectric layer and internal electrodes; forming a first electrode layer containing TiN (titanium nitride) on the front surface of the body by an atomic layer deposition method; forming a second electrode layer on a portion where first and second external electrodes are to be formed in the body on which the first electrode layer is formed; and etching and removing the exposed portion of the first electrode layer from the body on which the second electrode layer is formed.

First, referring to FIG. 7 , a step of preparing a body including a dielectric layer 211 and internal electrodes 221 and 222 may be performed.

A slurry formed including powder such as barium titanate (BaTiO ₃ ) is coated on a carrier film and dried to prepare a plurality of ceramic sheets.

The ceramic sheet is a slurry prepared by mixing ceramic powder such as barium titanate (BaTiO ₃ ), a binder, a solvent, etc., and the slurry can be prepared in a sheet form having a thickness of several μm through a doctor blade method. .

Next, a conductive paste containing a conductive metal may be prepared. The conductive metal may be nickel (Ni), copper (Cu), palladium (Pd), silver (Ag), lead (Pb) or platinum (Pt) alone or an alloy thereof, and has an average particle size of 0.1 to 0.2 μm. A conductive paste for internal electrodes containing 40 to 50% by weight of a conductive metal may be prepared.

Internal electrode patterns may be formed by applying the conductive paste for internal electrodes on the ceramic sheet by a printing method or the like. A screen printing method or a gravure printing method may be used as a printing method of the conductive paste, but the present invention is not limited thereto.

A laminate including the internal electrodes 221 and 222 may be formed by stacking the ceramic sheets on which the internal electrode patterns are printed, and stacking ceramic sheets on top and bottom of which the internal electrode patterns are not printed. In this case, the number of stacked ceramic sheets on which the internal electrode patterns are printed may be adjusted according to the capacity of the multilayer ceramic capacitor. The ceramic sheet on which the internal electrode pattern is not printed becomes the cover part 212 disposed on the upper and lower parts of the body 210 .

Thereafter, the body 210 may be formed by pressing and firing the laminate.

Referring to FIG. 8 , after the body 210 is formed, a first electrode layer 250 including TiN is formed on the entire surface of the body 210 by an ALD method.

Next, referring to FIG. 9 , a step of forming second electrode layers 232 and 242 is performed on the portion where the first and second external electrodes are to be formed in the body on which the first electrode layer 250 is formed.

For example, the second electrode layer may be formed by applying and firing a paste containing a conductive metal and glass.

In addition, a second electrode layer may be formed by applying a paste in which metal particles are dispersed to a base resin, and then drying and curing the paste.

In addition, a paste in which metal particles and a low melting point metal having a melting point lower than the curing temperature of the base resin are dispersed is applied to the base resin, and then dried and cured to form the second electrode layer.

Next, referring to FIG. 10 , a step of etching and removing the exposed portion of the first electrode layer 250 from the body on which the second electrode layers 232 and 242 are formed is performed to remove the first electrode layers 231 and 232 and A multilayer ceramic capacitor may be completed by forming the first and second external electrodes 230 and 240 including the second electrode layers 232 and 242 .

Since the second electrode layers 232 and 242 act as a passivation layer, the exposed portion of the first electrode layer 250 may be etched and removed without forming a separate passivation layer.

Also, etching may be dry etching or wet etching.

Thereafter, a step of forming a plating layer on the first and second external electrodes 230 and 240 may be additionally performed as needed, but is not limited thereto.

Although the embodiments of the present invention have been described in detail above, the present invention is not limited by the above-described embodiments and the accompanying drawings, and is intended to be limited by the appended claims.

Therefore, various forms of substitution, modification, and change will be possible by those skilled in the art within the scope of the technical spirit of the present invention described in the claims, which also falls within the scope of the present invention. something to do.

100: multilayer ceramic capacitor
110: body
111: dielectric layer
112: cover layer
121, 122: internal electrode
130, 140: external electrode
131: first electrode layer
132: second electrode layer

Claims (16)

A body including a dielectric layer and internal electrodes, and external electrodes disposed on one surface of the body,
The external electrode is
a first electrode layer disposed on one surface of the body, in contact with the internal electrode, and including titanium nitride (TiN); And a second electrode layer disposed on the first electrode layer; includes,
The first electrode layer has a thickness of 10 to 500 nm, and the second electrode layer includes at least one of a fired electrode including a conductive metal and glass and a resin-based electrode including a plurality of metal particles and a base resin, and the fired electrode or A resin-based electrode is disposed to contact the first electrode layer.
According to claim 1,
The first electrode layer is a multilayer ceramic capacitor formed by an atomic layer deposition method.
delete According to claim 1,
The body includes first and second surfaces facing each other, third and fourth surfaces connected to the first and second surfaces and opposed to each other, and connected to the first and second surfaces and connected to the third and fourth surfaces. It is connected to and includes fifth and sixth surfaces facing each other,
The internal electrodes include first and second internal electrodes alternately disposed such that one ends are exposed through the third and fourth surfaces with the dielectric layer interposed therebetween;
The external electrodes include first and second external electrodes disposed on third and fourth surfaces of the body and connected to the first and second internal electrodes, respectively.
According to claim 4,
The first and second external electrodes include connection parts formed on the third and fourth surfaces of the body, and band parts extending from the connection parts to parts of the first, second, fifth, and sixth surfaces of the body. , And a corner portion where the connection portion and the band portion contact,
Wherein the thickness of the connection portion of the first electrode layer is defined as t1 and the thickness of the corner portion of the first electrode layer is defined as t2, t2/t1 is 0.9 or more.
According to claim 1,
The second electrode layer is a sintered electrode including a conductive metal and glass.
According to claim 6,
The multilayer ceramic capacitor wherein the conductive metal is Cu.
According to claim 1,
The multilayer ceramic capacitor of claim 1 , wherein the second electrode layer is a resin-based electrode including a plurality of metal particles and a base resin.
According to claim 8,
The multilayer ceramic capacitor wherein the metal particles are at least one of Cu, Ni, and Ag.
According to claim 1,
The second electrode layer is a resin-based electrode including a plurality of metal particles and a base resin, and further comprises a conductive connection portion surrounding the plurality of metal particles and an intermetallic compound formed at an interface where the first electrode layer and the conductive connection portion come into contact. Multilayer ceramic capacitors.
According to claim 10,
Wherein the metal particles are at least one of Cu, Ni, Ag, Ag-coated Cu, and Sn-coated Cu.
According to claim 1,
The external electrode further includes a plating layer formed on the second electrode layer.
preparing a body including a dielectric layer and internal electrodes;
forming a first electrode layer containing titanium nitride (TiN) on the front surface of the body by an atomic layer deposition method;
forming a second electrode layer in contact with the first electrode layer on an upper portion of the body where the first electrode layer is formed and where the first and second external electrodes are to be formed; and
Etching and removing the exposed portion of the first electrode layer from the body on which the second electrode layer is formed,
The first electrode layer has a thickness of 10 to 500 nm, and the second electrode layer includes at least one of a fired electrode including a conductive metal and glass and a resin-based electrode including a plurality of metal particles and a base resin, and the fired electrode or A method of manufacturing a multilayer capacitor in which a resin-based electrode is disposed to contact the first electrode layer.
According to claim 13,
The second electrode layer is a method of manufacturing a multilayer capacitor formed by applying and firing a paste containing a conductive metal and glass.
According to claim 13,
The second electrode layer is a method of manufacturing a multilayer capacitor formed by applying a paste in which metal particles are dispersed in a base resin, followed by drying and curing.
According to claim 13,
The second electrode layer is formed by applying a paste in which metal particles and a low melting point metal having a melting point lower than the curing temperature of the base resin are dispersed in the base resin, followed by drying and curing.

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